I want more acceleration - not top end - ideas??

[Fabian]

My 2 cents

The best methods to improve acceleration (in the real world and not for racing applications) generally means increasing cylinder pressure in the low and mid range rpm's; typically displayed by the feeling of a torquier engine - It's torque that get's you moving.

The main ways to improve torque (from my own experience with messing around with 2-stroke engines) is to leave the exhaust pipe as standard or (if you can get away with it) choose a tuned pipe that's designed to operate at low to mid range rpm.

Run the standard NT carburettor just on the rich side to prevent detonation at low rpm with wide open throttle.
Match port all the internal air/fuel pathways from the carburettor to the air/fuel destination in the cylinder head and match port the exhaust flange to the exhaust port.
Use some method of attaching a reed valve intake system to the intake port.

But the best method of improving torque output at lower rpm's is to increase engine capacity.

Fabian

 

[motorpsycho]

Changing your gear ratio is the fastest, cheapest and easiest thing to do to increase acceleration. I went from a 44 tooth rear sprocket down to a 41 tooth because i am using 20" wheels. with the 44 tooth sprocket and small wheels, my engine would accelerate fast, but it would peak way before it ever got up to speed. I mean i was getting about 25 mph top speeds but the motor would be screaming at that speed. I dropped to the 41 tooth sprocket, which raised the torque peak. my bike accelerates faster and has more top speed now (28.7 mph) BUT, the big difference was getting from 0 mph to top speed. Now it does it faster because my torque peak has moved due to the smaller rear gear. it can now use the torque curve better and it's not so much a peak now, it's more like a constant pull across the mid range rpms.
it's hard to explain, but it is one of 2 changes that i've done that has made the biggest difference. the other change that made a big difference was adding an expansion chamber with a modified stock muffler (this set up works awesome and sounds awesome...this made quite an increase in power over the stock muffler). I have a high flow air filter, ngk 6HS spark plug, and an accell superstock plug wire and boot. I found that my engine runs best on a 32:1 ratio and i am using synthetic 2 stroke oil and 87 octane gas. I have yet to mill the head or port match the intake and exhaust. bit maybe one day i will get around to it.
oh, did i mention that my motor is only a 49 c.c. and i can out-run my friend's 80 c.c. with no problem? the disadvantage that i have as comapaired to most other bikes is that I am using the 20" wheels on a 20" frame. 20" wheels will not give as much top end speed as a set of 26" wheels will. plus, these kits were designed to be used on 26" bikes with 26" wheels. the 44 tooth sprocket and gear ratio were designed for use on 26" wheels

 

[PatrickW]

Rad Mods vs More Simple Solutions...

CARROT - THE DESTROYER...I think that Dave (srdavo) hit this smack on the head (if you will) in his post. If you are contemplating doing anything (drastic, such as milling the head, boring, stroking, etc)...remember that you are really dealing with a rather delicate, balanced, small 2-stroke engine made mostly of aluminum or like alloy. If you are going to start the fancy 'hot-rod' type mods, you are going to tremendously increase the strain on the cylinder, head, wrist pin, con rod, crank, and even 'what they tout' as those super-extra-heavy-duty Chinese needle bearings. If you over-do it, and it doesn't have to be by much, I can flat guarantee that you will have shrapnel, motor parts and maybe some body parts flying in all directions. I know this first hand from running many a quarter mile in tricked out vehicles.

Moral: Just take it slow and easy; be careful and cautious; and start with the seemingly simple and easy stuff first (like gearing, exhaust, and clamping that motor solid to the frame for max power transfer. Leave any internal stuff to a well qualified machine shop.

I hope I didn't come off as too redundant or pedantic, here. Just want to help. Good Luck

PatrickW

 

[nobullcraptalk]

Why not save up and either get a four stroke from gebe or ezm or buy a quality 2 stroke morini and be done with the headache china girls pose being they are what they are.Temporary basic motors with no room to modify without having problems.

 

[cabinfever1977]

Buy a larger rear sprocket for faster exceleration and more torque,like a 50t,and you will be doing wheelies.
A smaller rear sprocket is less torque and accleration but more top end speed and lower rpms.